In the treatment of many illnesses, it is necessary to repeatedly infuse medication directly into the bloodstream, into a particular organ, or otherwise to a particular medication site. For example, various chemotherapy regimes for treatment of cancerous conditions require frequent periodic medication. Bowel diseases and bone infections are other examples of conditions which require repeated treatment, as does the periodic dispensing of pain medication for terminally ill patients. In such frequent medication situations, to avoid having to locate a blood vessel for injection by needle each time, it is preferred to implant a catheter into the circulatory system through which the medication can be infused. Likewise, catheters are implanted to dispense medication directly to diseased or other treatment sites. Often, the medication is toxic in concentrated amounts and, therefore, must be infused through a catheter into a large volume of blood. To accomplish this, the catheter is fed through a vessel to a large vein or a chamber of the heart. Catheters are also used for dispensing dialysis fluid to the peritoneal cavity for the purpose of peritoneal dialysis
Various removable devices have been developed to administer medications to the large veins in the body or to a chamber in the heart, including external extending catheters, such as those referred to as BROVIAC, GROSHONG, and HICKMAN catheters. Another general type of system which is wholly implanted is generally referred to as a vascular port, such as, for example, PORT-A-CATH®, available from Pharmacia Deltec, Inc., St. Paul, Minn., or as disclosed in U.S. Pat. No. 5,281,205 to McPherson, or VITAL-PORT® available from Cook Inc. of Bloomington, Ind.
A problem that arises with some implanted vascular access systems is that, despite steps taken after they are used to keep them clean, the patient may become infected at the site where the catheter is inserted. Given sufficient time, any catheter system that leaves the access opening external of the body will necessarily develop infection at the site where the catheter passes through the skin. While fully implanting a catheter device may reduce the problem of infection, other devices which are fully implanted require more invasive surgery, resulting in more discomfort, greater expense, and a longer recovery period. Moreover, these invasive techniques tend to form unsightly scars and scar tissue.
Tunneled catheters help reduce the chance for infection. Externally extending catheters are typically implanted using a guidewire, which is inserted through a first, vena-puncture incision into a patient's body and directed to the point of application, e.g., a vein or an organ, through the lumen of a needle. Once the guidewire is in place in the vein or organ, a peelaway sheath is fitted on a dilator and guided distally over the guidewire by the dilator. When the dilator is withdrawn, the sheath forms a tunnel through the first incision to the point of application. A tunneler having the proximal end affixed to a catheter, such as a dialysis catheter, is inserted into a second incision about 5 to 10 cm from the first incision, and the distal end of the tunneler is worked subcutaneously to the first incision, where the tunneler and catheter distal end are pulled out of the first incision. Then, after the distal end of the catheter is disengaged from the tunneler proximal end, the catheter distal end is inserted into the sheath proximal end. The catheter is pushed through the sheath to the point of application, the sheath is peeled away, and the first incision is closed, so that the catheter extends from the second incision to the point of application.
The above-described procedure has a number of disadvantages. For example, air embolization is a major potential complication. Also, there is the trauma associated with making two incisions, which could result in additional scarring and/or infection. Further, there is a potential technical problem of “kinking” the catheter during insertion. In addition, this procedure is somewhat time-consuming, taking from about 30 to 60 minutes to complete.
Tunneled catheters are used for the purpose of dialysis. For hemodialysis a tunneled double lumen catheter is placed in the veins of the chest, usually the jugular or subclavian veins, with the tip of the catheter in the superior vena cava or the right atrium. For peritoneal dialysis a tunneled single lumen catheter is placed into the peritoneal cavity with the tip usually in the pelvis.